Conventionally, there is provided a technique for detecting a paper jam in the field of image forming apparatus. In the technique, it is common practice to perform paper jam determination (jam determination) on the basis of whether or not a medium for recording being conveyed is moved between predetermined positions within a predetermined period of time.
The above described jam detection can be specifically performed by providing detecting devices for detecting a medium for recording at two positions in a conveyance path, respectively. For example, it is possible to determine that the paper jam is caused, when the medium for recording passes through one of the detecting devices and thereafter does not pass through the other detecting device within a predetermined period of time. However, in the case of the constitution in which the paper jam is determined on the basis of the detection by the two detecting devices, there is a problem that when the power supply of the image forming apparatus is interrupted in the state where the medium for recording is jammed between the two detecting devices, the redetection of the medium for recording cannot be performed. For example, when the power supply is interrupted in the state where the medium for recording is jammed between the two detecting devices, the paper jam cannot be detected because the medium for recording is not detected by any of the detecting devices when the power supply is turned on at the next time.
Thus, there is a need in the art for an image forming apparatus capable of suitably locating a medium for recording existing between two detecting devices.